


Sicko

by TheMsource



Series: Sicko [1]
Category: Undertale (Video Game)
Genre: Angst, Creep!Sans - Freeform, Don't Read This, F/M, Gross, Obsession, Reader Is Not Chara (Undertale), Reader Is Not Frisk (Undertale), Sans is sick, Sex, Smut, Unhealthy Relationships, Unrequited Love, my brain is messed up, seriously dont click on it
Language: English
Status: Completed
Published: 2019-03-10
Updated: 2019-03-10
Packaged: 2019-11-14 20:20:40
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,780
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18059399
Author URL: https://archiveofourown.org/users/TheMsource/pseuds/TheMsource
Summary: Sometimes you wonder how you ended up here; beneath a skeleton...Series Inspired by Creep - KenyaKetchup





	Sicko

**Author's Note:**

> DO NOT READ IF YOU ARE SENSITIVE ABOUT FRANS RELATED CONTENT OR ANYTHING IMPLYING UNDERAGE LUST
> 
> Seriously you probably shouldn't read this anyways...
> 
> This was literally just a passing thought in my head.
> 
> Post-pacifist Ending.

Sometimes you wondered how you ended up here; beneath a skeleton as he pounded into you relentlessly, his hard phalanges dragging down and leaving delicate welts in your pale skin. His heated breath panting forcibly against your sweat soaked neck. 

“Oh Frisk~ you feel so good…” He groaned. You felt a disgusting shiver of pleasure run through you, at the name that wasn’t yours. A sick part of you enjoying the thought of being his dirty little secret. Your heart slammed in revulsion and joy.

_It hadn’t alarmed you when you’d first run into each other, he’d seemed like a normal monster donning the usual friendly and compassionate nature that they tended to exude. You’d even felt joy when he’d asked you to join him for some coffee, his jokes and various puns endearing to hear. You’d even loved it when he lit up at the mention of his brother and kid a serene peace coming over his face. It wasn’t until a simple statement he made that sent up the first red flag._

_“you know…you’re kinda how i imagine my kid will look when she grows up.” You saw for but a moment a flicker of something dark, something perverse but it had quickly vanished, replaced with his perpetual lazy grin. You awkwardly thanked him but brushed it off. He obviously held Frisk in high regard and he didn’t seem to be hitting on you or anything. Maybe you imagined that look?_

“you love this don’t you? me using you like the cock sleeve you are.” He growled as he ran his tongue along your jugular, the action making your walls clamp down on him harshly. He groaned as he leaned up and gripped your breasts, his hands massaging the sensitive flesh as he flicked your nipples. You moaned under his touch, your morals twisting sickeningly at the jolts of pleasure in your chest.

“oh I hope her breasts are as beautiful as yours when she matures…so soft and delicate.” His voice pitched low with adoration and love. Adoration and love for another. For his kid. You hated yourself for letting him touch you, for letting him live out this sick fantasy. Unfortunately you would’ve hated yourself more if you had denied him. 

_The second red flag happened when you’d both been hanging out for a while. You’d both been drinking coffee like usual talking about work and life. But his face had gone dark when you’d inquired about Papyrus and Frisk. Papyrus had been fine, gotten a new job at the pet store. Frisk though…Frisk had gotten her first boyfriend. You had to stop yourself from jumping when he’d crushed his empty cup in his hand._

_You foolish as you were chalked it up to protective parenting. You’d given him a reassuring smile saying she was still young, he didn’t have to worry to much about anything inappropriate. He’d sat quietly, a distant look in his sockets and then changed the subject. You felt your heart ache at the sadness he’d shown but went along with the subject change._

“oh I can feel you…you’re so close kiddo..!” He grunted as your body began to tighten and your walls fluttered against him. You moaned his name as his pace quickened, his cock hitting that sensitive bundle of nerves inside you perfectly. You felt your breathing become ragged as you gripped his shoulders desperately, as if your soul would float away. 

The final red flag…

_You’d been crying. You’d huddled in on yourself outside the closed coffee shop on a bench, the chilly night air biting into your face against the onslaught of warm tears. You’d gone there for comfort, the passing thought of Sans being associated with it drawing you. Just as you had contemplated your stupidity and thought about leaving you’d felt a bony hand on your shoulder. Your head had shot up to skeletal sockets watching you full of concern. You wept harder. Sans had sat next to you and carefully drew you into his arms._

_“shhh…it’s ok I’m here.” He had cooed as he rubbed small circles into your back. The warmth from his body calming you down to sniffles. Finally you told him how you’d been fired that day and your brother had kicked you out. It had come out in a torrent. He was calm, he listened. When you were finished he smiled and promised he’d help you get through it. It was then you’d realized you’d loved him. It had taken a week but he’d helped you back to your feet, you’d met Papyrus and Frisk finally. They were exactly as he’d described them and more._

_One night though when you’d been visiting his face had suddenly become cold and his body stiffened. Frisk had just got done informing everyone that she was going on a date that night. You’d watched perplexed as Sans forced on a casual smile and asked Frisk into the kitchen privately. Papyrus had mentioned going to get a game from his room leaving you alone. At first you’d heard mumbling that gradually turned strained and then broke into outright shouting. You’d leapt up and rushed to the kitchen, stalling as Frisk rushed past you and out the door slamming it behind her. Sans was standing still his sockets focused on a spot of the kitchen floor, eyelights gone._

_You’d approached him slowly, your hand gently coming to rest on his shoulder. He reluctantly looked towards you as his eyelights returned tired and full of pain. You asked if he wanted to talk about it. He paused and finally nodded leading you up to his room. You knocked on Papyrus’s door and told him you needed to talk to Sans so he wouldn’t worry. Once in his room Sans had slumped onto the side of his bed where you joined him._

_You'd waited silently until he finally just let it out. His fear of how dangerous dating could be for Frisk, his frustration that she insisted on doing the whole thing period, how he felt like she enjoyed making him feel like this, and how she felt no guilt at how it was affecting him. You did as he had and rubbed small circles into his back comfortingly. After all you couldn’t really say anything, you had no idea what parenting was like anyways._

_It was when a single tear had slipped from his eye that you’d cupped his cheek and turned his skull towards you. Promising Frisk loved him and didn’t mean to hurt him, she was growing and was adjusting, like all normal children. His expression had become unreadable and slowly he’d brought up his hands to cup your cheeks, your heart skipping as he leaned in and kissed you.  
It had been soft, gentle and wary._

_Slowly you’d reciprocated and kissed him back, his kiss switching to desperate and hungry. Your heart had slammed, the man you’d fallen for was kissing you! You remembered how warm you’d felt, how excited you were as he fell back with you into the mattress, his hands quickly slipping under your shirt and pulling you flush to him. It was everything you’d dreamed of as he kissed you, heat pooling and coiling in you as you reached under to stroke his ribs. It was when he moaned that you froze._

_“frisk…” You’d pulled away and you’d ran. Your heartbreak was nothing to the shock and nausea that had hit you in that instant. You ignored his call for you and had rushed from his house blindly. You didn’t stop running till you were out of breath. You sighed in relief once you’d made it home and then had promptly gone in and fell to your bed crying. You’d fallen for a sicko, a fucked up morally twisted monster. It was only a week before you’d heard the knock on your door, opened it to find Sans tired and broken looking. You’d wanted to slam your door in his face, curse obscenities at him. But the moment his eyelights locked with yours you melted._

_It was like a knife to your gut, you still loved him and it hurt to see him this way. Reluctantly you invited him in, with disgust you let him sit close to you on your couch. It took prompting but he finally let you know what was bothering him, he’d caught Frisk having sex…with a boy that wasn’t even her boyfriend. You wanted to rant at him how it shouldn’t bother him, how it was sick how he felt to begin with, but you could only feel the unwanted sympathy flood in and you slowly touched his shoulder._

_You didn’t speak as he looked at you, didn’t move as he reached for you. You knew now what that kiss had been, he had said he saw Frisk in you, you knew what this embrace was, an attempt to pretend he was normal that the little girl he was sickeningly lusting after was already an adult. That he could have her. You felt the sane part of you scream to push him away to chase him out, but the dark part, the fucked up part that still loved him…made you pull him close. It gave in._

_It became a cycle, he’d get upset with Frisk or depressed over something she said or did. Then he’d show up here pulling you into his arms. You didn’t fight, didn’t resist. You were resigned that this love was one sided, that he only wanted her. Loved and adored only her. In your minds sad attempt to deal with the fucked up thing you were doing it began to like it. The way he’d say her name, how harshly or gentle he’d handle you, the way he’d degrade you as he used you. It wasn’t his love, but it was something._

“oh yes…cum for me you dirty slut…” He growled as he nipped your shoulder, drawing and in turn lapping away the blood. Your vision tunneled as you reached your peak. His movements became uncoordinated and rough as he thrusted into you. Delicious sparks of his magic flickering along your walls and skin as he chased his own orgasm.

“i want to imagine what she feels like. i want to know how Frisk would feel, her walls slamming on my cock as i fill her…cum!” On command your body broke, locking up and twitching as your vision went white and a strangled groan spilled from your lips. 

“f-fuck!” Sans chocked as his grip tightened on your sheets, the sound of tearing fabric filling the air as he gasped. You barely felt his magic flood into you as your body began to slowly come down from it’s high, sore and satisfied. His cock dissipated and slowly he moved off of you, the cold chill of your room harsh against your heated body. You ignored the passing look of guilt on his face. You knew it wasn’t meant for you, it was meant for her. The thought he was betraying her never failing to flood his mind after these acts between you. It hurt. You watched brokenly as he started to dress. He was leaving. He never stayed afterwards. Pretending you weren’t going to cry about this again later you got up and slipped on a robe, casting a broken glance to his back.

You supposed what hurt the most was how he no longer invited you over, no longer bonded with you over coffee or anything. But you knew, he felt ashamed. He felt like he was cheating on frisk. It made you feel gross. But you knew you wouldn’t give this up, no matter how fucked you were in the head. You didn’t want to lose his touches, those rare moments during where it looked like he might actually be looking at you…not imaging a fifteen year old beneath him. 

You left him to dress as you made your way to the kitchen. Numbly you started your coffee machine and turned on your tv to Netflix. This was your coping mechanism, pretend you were hanging out like the old days and watch some shitty rom-coms. You blinked as the machine dinged signaling it was ready. You brought down a mug and filled it, trying your hardest to prevent the tears till after Sans had left. You involuntarily stiffened as you heard your bedroom door close. 

You looked up as sans glanced at the tv and towards you, a look of pity in his eyelights. He knew what you were doing, you set up for it everytime after all. You smiled weakly at him and turned your eyes back down as you added sugar to your cup, waiting for the sound of the front door. It didn’t come.

You furrowed your eyebrows and looked back up at him. He had moved a step towards you, his posture awkward and shy. You watched him in confusion. He held a fist up and coughed into it awkwardly, a tiny version of his perpetual grin on his face. You hated how it made your stomach feel like it had butterflies. 

“you uh…want some company?” You startled slightly. He never stayed, never offered. He ALWAYS left. You gulped nervously as a tiny speck of hope bloomed in your chest. You knew it shouldn’t, it was dangerous to hope he might actually feel something for you. And he was sick, you shouldn’t hope for anything when it came to him. But here he was, offering his company. Offering his time. You noticed him shuffle uncomfortably from your staring. You looked at him weakly, hesitantly.

“Sans…have you ever…actually touched Frisk?” His sockets widened in surprise at the question. He searched your face a moment, his eyes lowering sadly. Slowly he looked back up at you, his smile gentle but yet strained.

“ **no.** i haven’t.” That was…not the answer you were expecting. You knew he had a sick obsession with her, he loved her in the wrong way. But yet he hadn’t ever laid a finger on her? You guessed that maybe some part of what you two were doing helped. You hoped. Timidly you turned away and pulled down another mug and filled it. He’d always liked it black. 

You held it out to him. His eyelights stared at the offered drink a moment and slowly he reached out and took it. You made your way to the couch and held up the blanket already on it, patting the empty space next to you under it. You held your breath as he drifted over and lowered himself next to you. It was tense, but you couldn’t suppress the smile on your face as you scooted close and covered him. He didn’t bolt, didn’t look uneasy. He even let you lean against him as you got comfortable. He chuckled. You felt your soul do flips in your chest. 

“What are you up for?” You asked happily as you browsed through the options. You didn’t notice his blush nor the arm he slung on the back of the couch behind you.

“anything that isn’t a superhero movie.” You laughed thinking back on Papyrus’s movie collection. You finally selected something and relaxed, savoring the domestic feeling in the air. This was what you wanted, this was your dream. He was sick and fucked up, but there had to be some light in there right? He’d stayed over unprompted; he was letting you cuddle him. 

Is it possible he did care about you? Could he be redeemed? You guessed you’d have to wait and see, Frisk’s eighteenth birthday was in three years. You had time; maybe you could help him, get him therapy. Maybe you could both be happy together? Maybe…you felt the tears trying to come. It was naive to believe you could help him; he was so in love with her. You wish you could understand what made Frisk so special to him, you wish you could be the one he loved. You fought down the tears as you felt him shift slightly.

You couldn’t suppress the sigh that escaped as you felt his phalanges running through your hair. You glanced up to see he was fully focused on the movie, lazily sipping his coffee. You realized even if you couldn’t save him, help him realize how sick he was. It wouldn’t matter. You had three years. You were going to take every moment you could get. And just maybe you could get him to understand…you were here for him…he didn’t need to feel so alone. You loved him…this poor demented sicko.


End file.
